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# Fourier: frequency domain feature in the time domain Watch

1. Hello,

I have a frequency-domain signal and will do a reverse fourier transform to get it in the time domain. there's a feature I'm interested in and I know where it is in the frequency domain (ie, which characteristic frequency the event happens at), I was wondering how I get that feature in the time domain.

Kind regards.
2. (Original post by x345)
Hello,

I have a frequency-domain signal and will do a reverse fourier transform to get it in the time domain. there's a feature I'm interested in and I know where it is in the frequency domain (ie, which characteristic frequency the event happens at), I was wondering how I get that feature in the time domain.

Kind regards.
Your question is too vague to have a unique answer (or maybe I don't understand it properly)

If your frequency domain signal is a single spike, say, then the "feature" is a sine wave in the time domain, which you can then point at.

If your time domain signal is a repetitive square wave, then its FT will be a bunch of discrete frequencies, whose amplitudes can be computed from Fourier analysis. But there is now no one-to-one correspondence between part of the frequency domain, and what you will see in the time domain.

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Updated: June 9, 2016
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